1. Field of the Invention
The present disclosure relates to a holography three dimensional display in which no 3D cross-talk problem is arisen. Especially, the present disclosure relates to an autostereoscopy type display without any 3D cross-talk problem in which the left eye holography image is presented to the left eye and the right eye holography image is presented to the right eye, separately.
2. Discussion of the Related Art
Recently, many technologies and researches for making and reproducing the 3D (Three Dimensional) image/video are actively developed. As the media relating to the 3D image/video are new concept for media providing virtual reality, the media relating to the 3D image/video can improve the visual information, and will lead the next generation display devices. The conventional 2D image system merely provides the image and video data projected to a planar view, but the 3D image system can provide the full real image data to the viewer. So, the 3D image/video technologies are the future directions of image/video technologies.
Typically there are some methods for reproducing 3D image/video; for example, the stereoscopy method, the autostereoscopic method, the volumetric method, the holography method and the integral imaging method. Among them, the holography method, in which the observer can see the holography image using LASER without special glasses, is the best method for enjoying the real 3D display quality. As the holography method has superior 3D depth and the observer can see the display object in 3D mode even with one eye, it is supposed to be the most ideal method for displaying 3D images without any demerit.
To produce a recording of the phase of the light wave at each point in an image, holography method, one of volumetric display types, uses a reference beam which is combined with the light from the scene or object (the object beam). If these two beams are coherent, optical interference between the reference beam and the object beam, due to the superposition of the light waves, produces a series of intensity fringes that can be recorded on standard photographic film. These fringes form a type of diffraction grating on the film, which is called the hologram. The central goal of holography is that when the recorded grating is later illuminated by a substitute reference beam, the original object beam is reconstructed (or reproduced), producing a 3D image/video.
There was a new development of the computer generated holography (or CGH) that is the method of digitally generating holographic interference patterns. A holographic image can be generated e.g. by digitally computing a holographic interference pattern and printing it onto a mask or film for subsequent illumination by suitable coherent light source. The holographic image can be displayed by a holographic 3D display, bypassing the need of having to fabricate a “hardcopy” of the holographic interference pattern each time.
Computer generated holograms have the advantage that the objects to be displayed do not have to possess any physical form at all. If holographic data of existing objects is generated optically, but digitally recorded and processed, and displayed subsequently, this method is termed CGH as well. For example, a holographic interference pattern is generated by a computer system and it is sent to a spatial light modulator such as Liquid Crystal Spatial Light Modulator (LCSLM or SLM), then the 3D image/video corresponding to the holographic interference pattern is reconstructed/reproduced by radiating a reference beam to the spatial light modulator. FIG. 1 is the structural drawing illustrating the digital holography image/video display device using the computer generated holography according to the related art.
Referring to FIG. 1, the computer 1 generates a holographic interference pattern of an image/video data to be displayed. The generated holographic interference pattern is sent to a SLM 2. The SLM 2, as a transmittive liquid crystal display (LCD) device, can represent the holographic interference pattern. At one side of the SLM 2, a laser source 3 for generating a reference beam is located. In order to radiate the reference beam 9 from the laser source 3 onto the whole surface of the SLM 20, an expander 4 and a lens system 5 can be disposed, sequentially. The reference beam 9 out from the laser source 3 is radiated to one side of the SLM 2 passing through the expander 4 and the lens system 5. For the case that the SLM 2 is a transmittive type liquid crystal display, a 3D image/video corresponding to the holography interference pattern will be reconstructed/reproduced at the other side of the SLM 2.
The conventional holography type 3D display includes bulky elements occupying large space such as laser source 3 generating the reference light 9, the expander 4 and the lens 5. With these bulky elements, the conventional holography type 3D display has large volume and heavy weight, so that it is not proper for a light, thin, and portable type display. Therefore, it is required to develop an autostereoscopy type thin panel holography 3D display.
In the case that the hologram is reproduced based on the LCD device, the pixel pitch of the LCD is too large, so that the proper viewing angle of the hologram is very limited. Therefore, the observer can see the hologram 3D images just within the very small viewing angle.